After increasing the replication level, I still see that data is under replicated. What could be wrong? | Hadoop admin questions

Data replication takes time due to large quantities of data. The Hadoop administrator should allow sufficient time for data replication
Depending on the data size the data replication will take some time. Hadoop cluster still needs to copy data around and if data size is big enough it is not uncommon that replication will take from a few minutes to a few hours.